Sadly, these Ms cost so much money now, and still have a ways to go compared to the latest DSLR sensors that I have to consider resale value.

As of today, an M8.2 at $3300 seems fair for Ex+ and Silver body. The Silver bodies currently seem to go for about $500 more then the Black Paint ones from what brief research I've done. Although if kept pristine Black Paint bodies seem worth more over time... but down the road that might not be such a premium since I think M8s will all drop as newer FF bodies are released. Will Leica M8s be the Leica CL of the future used market? M8s are a different user experience then FF, just as the CL form factor is a different user experience then an M. M8s will all spec lower in IQ compared to future bodies (all being FF), and the CL doesn't even suffer that comparison to any other film M bodies.

I think I'm talking myself into hunting down an M9...

The M9, if I can get a really good deal, I think is more likely to hold it's value because it's full frame and future bodies will all be full frame. In the near term, the quantitative differences will be in ISO speed and crazy resolution for making super huge prints (which I think are both criteria important to a smaller percentage of full frame shooters). Of course a big improvement in dynamic range might trump my theory, but I think it's a better bet then going with the M8.2